Effects of sodium hydrosulfide (NaHS) on cisplatin-induced hepatic and cardiac toxicity.

In recent years, the cardiotoxicity and hepatotoxicity induced by chemotherapeutic drugs such as cisplatin (CP) have become significant issues. The current research looks into the effects of sodium hydrosulfide (NaHS) on CP-induced hepatotoxicity and cardiotoxicity in rats. A total of 32 male Sprague Dawley rats were separated into four different groups: (1) control group, received only normal saline; (2) NaHS group, was intraperitoneally injected with NaHS (200 µg/kg/d, dissolved in saline) for 15 days; (3) CP group, was intraperitoneally injected only one dose of CP (5 mg/kg) and (4) CP plus NaHS group, received CP along with NaHS. Blood and tissues samples were harvested for biochemical, histopathological, and immunohistochemical investigations. To determine the data's statistical significance, a one-way analysis of variance was used. CP injection significantly increased alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), Creatine phospho kinase (CK-MB), cholesterol, low-density lipoprotein (LDL), triglyceride (TG), and lipid peroxidation levels, while high-density lipoprotein (HDL), albumin, glutathione peroxidase, superoxide dismutase, and catalase (CAT) levels were significantly reduced with pathological alterations in liver and heart tissues. Co-treatment NaHS with CP ameliorates the biochemical and histological parameters. Also, Treatment solely with CP resulted in increased tissue expression of interleukin-1ß (IL-1ß) in liver and heart but co-treatment NaHS with CP reduced the expression of this inflammatory factor. We conclude that NaHS operates in the liver and heart as an anti-inflammatory and powerful free radicals' scavenger to inhibit the toxic effects of CP, both at the biochemical and histopathological levels.

NaHS protects the liver and heart against Cisplatin-induced toxicity.

Mitigating salt toxicity and overcoming phosphate deficiency alone and in combination in pepper (Capsicum annuum L.) plants through supplementation of hydrogen sulfide.

While it is widely recognized that hydrogen sulfide (H2S) promotes plant stress tolerance, the precise processes through which H2S modulates this process remains unclear. The processes by which H2S promotes phosphorus deficiency (PD) and salinity stress (SS) tolerance, simulated individually or together, were examined in this study. The adverse impacts on plant biomass, total chlorophyll and chlorophyll fluorescence were more pronounced with joint occurrence of PD and SS than with individual application. Malondialdehyde (MDA), hydrogen peroxide (H2O2), and electrolyte leakage (EL) levels in plant leaves were higher in plants exposed to joint stresses than in plants grown under an individual stress. When plants were exposed to a single stress as opposed to both stressors, sodium hydrosulfide (NaHS) treatment more efficiently decreased EL, MDA, and H2O2 concentrations. Superoxide dismutase, peroxidase, glutathione reductase and ascorbate peroxidase activities were increased by SS alone or in conjunction with PD, whereas catalase activity decreased significantly. The favorable impact of NaHS on all the evaluated attributes was reversed by supplementation with 0.2 mM hypotaurine (HT), a H2S scavenger. Overall, the unfavorable effects caused to NaHS-supplied plants by a single stress were less severe compared with those caused by the combined administration of both stressors.

Hydrogen Sulfide Promotes Postnatal Cardiomyocyte Proliferation by Upregulating SIRT1 Signaling Pathway.

Hydrogen sulfide (H2S) has been identified as a novel gasotransmitter and a substantial antioxidant that can activate various cellular targets to regulate physiological and pathological processes in mammals. However, under physiological conditions, it remains unclear whether it is involved in regulating cardiomyocyte (CM) proliferation during postnatal development in mice. This study mainly aimed to evaluate the role of H2S in postnatal CM proliferation and its regulating molecular mechanisms. We found that sodium hydrosulfide (NaHS, the most widely used H2S donor, 50-200 µM) increased neonatal mouse primary CM proliferation in a dose-dependent manner in vitro. Consistently, exogenous administration of H2S also promoted CM proliferation and increased the total number of CMs at postnatal 7 and 14 days in vivo. Moreover, we observed that the protein expression of SIRT1 was significantly upregulated after NaHS treatment. Inhibition of SIRT1 with EX-527 or si-SIRT1 decreased CM proliferation, while enhancement of the activation of SIRT1 with SRT1720 promoted CM proliferation. Meanwhile, pharmacological and genetic blocking of SIRT1 repressed the effect of NaHS on CM proliferation. Taken together, these results reveal that H2S plays a promotional role in proliferation of CMs in vivo and in vitro and SIRT1 is required for H2S-mediated CM proliferation, which indicates that H2S may be a potential modulator for heart development in postnatal time window.

The hepato-protective effect of H2S-modified and non-modified mesenchymal stem cell exosomes on liver ischemia-reperfusion injury in mice: The role of MALAT1.

INTRODUCTION: Ischemia-reperfusion injury (IRI) by causing histopathological changes is considered one of the most important causes of liver failure and dysfunction after surgery which affect graft outcomes. Stem cells are new promising approaches to treating different diseases. One of the critical strategies to improve their function is the preconditioning of their culture medium. This study compared the effect of NaHS-modified and non-modified mesenchymal stem cell exosomes on liver ischemia-reperfusion injury in mice. METHODS: Human umbilical cord-derived MSC (MSC) cultured in a 75 cm3 flask and when confluency reached about 80%, the culture medium replaced with a serum-free medium, and 48 h later supernatants collected, concentrated, and then MSC-Exo extracted. To obtain H2S-Exo, MSC was treated with NaHS (1 µmol),the supernatant collected after 48 h, concentrated and exosomes extracted. Twenty-four male mice were randomly divided into four groups (n = 6) including: 1-ischemia, 2-sham-operated, 3- MSC-Exo, and 4- H2S-Exo. To induce ischemia, the hepatic artery and portal vein clamped using an atraumatic clip for 60 min followed by 3 h of reperfusion. Just upon ending the time of ischemia (removal of clamp artery), animals in MSC-Exo, and H2S-Exo groups received 100 µg exosomes in 100 µl PBS via tail vein. At the end of reperfusion, blood, and liver samples were collected for further serological, molecular, and histological analyses. RESULTS: Administration of both MSC-Exo and H2S-Exo improved liver function by reducing inflammatory cytokines, cellular apoptosis, liver levels of total oxidant status, and liver aminotransferases. The results showed that protecting effect of MSC exosomes enhanced following NaHS preconditioning of cell culture medium. CONCLUSION: MSC-Exo and H2S-Exo had hepato-protective effects against injuries induced by ischemia-reperfusion in mice. NaHS preconditioning of mesenchymal stem cells could enhance the therapeutic effects of MSC-derived exosomes.

Sodium hydrosulfide inhibiting endothelial cells injury and neutrophils activation via IL-8/CXCR2/ROS/NF-κB axis in type 1 diabetes mellitus rat.

AIMS: Hydrogen sulfide (H2S) prevents endothelial cells injury. However, the complicated mechanism of sodium hydrosulfide (NaHS, a donor that produces H2S) which inhibits the endothelial cells injury which correlated the activation of neutrophil in the type 1 diabetes mellitus (T1DM) rats has not been previously investigated. METHODS AND RESULTS: In the experiment, the T1DM animal model was established, the IL-1ß, IL-8 were determined by western blotting and ELISA, the expressions of the Bax and Bcl-2 of endothelial cells and the CXCR2, CSE, phosphor-IκBα and NF-kB of neutrophils were measured by western blotting. Additionally, the concentration of serum dsDNA was tested by PicoGreen commercial Kits, changes in the H2S concentration of neutrophils were determined by Multiskan spectrum microphate spectrophotometer, the cellular ROS levels of neutrophils were detected by DCFH-DA staining and flow cytometry. The IL-1ß, IL-8 concentration and expression increased, the endothelial cells injury which stimulated by high glucose and the concentration of dsDNA in serum increased, the expression of CXCR2, phosphor-IκBα and NF-kB increased while the expression of CSE and concentration of H2S decreased in neutrophils in the T1DM group compared to the control group. NaHS significantly inhibited the injury of endothelial cell, the production of ROS in neutrophils, reversed the expressions of CXCR2, CSE, phosphor-IκBα and NF-κB and decreased concentration of dsDNA in serum which were caused by T1DM. CONCLUSIONS: Our results demonstrated that the donor of H2S inhibits endothelial cells injury and neutrophils activation via the IL-8/CXCR2/ROS/NF-κB axis in T1DM rat.

Hydrogen sulfide decreases photodynamic therapy outcome through the modulation of the cellular redox state.

Photodynamic therapy (PDT) is a non-surgical treatment that has been approved for its human medical use in many cancers. PDT involves the interaction of a photosensitizer (PS) with light. The amino acid 5- aminolevulinic acid (ALA) can be used as a pro-PS, leading to the synthesis of Protoporphyrin IX. Hydrogen sulfide (H2S) is an endogenously produced gas that belongs to the gasotransmitter family, which can diffuse through biological membranes and have relevant physiological effects such as cardiovascular functions, vasodilatation, inflammation, cell cycle and neuro-modulation. It was also proposed to have cytoprotective effects. We aimed to study the modulatory effects of H2S on ALAPDT in the mammary adenocarcinoma cell line LM2. Exposure of the cells to NaHS (donor of H2S) in concentrations up to 10 mM impaired the response to ALA-PDT in a dose-dependent manner. The addition of 3 doses of NaHS showed the highest effect. This decreased response to the photodynamic treatment was correlated to an increase in the GSH levels, catalase activity, a dose dependent reduction of PpIX and increased intracellular ALA, decreased levels of oxidized proteins and a decrease of PDT-induced ROS. NaHS also reduced the levels of singlet oxygen in an in vitro assay. H2S also protected other cells of different origins against PDT mediated by ALA and other PSs. These results suggest that H2S has a role in the modulation of the redox state of the cells, and thus impairs the response to ALA-PDT through multifactor pathways. These findings could contribute to developing new strategies to improve the effectiveness of PDT particularly mediated by ALA or other ROS-related treatments.

Nephroprotection through Modifying the Apoptotic TNF-α/ERK1/2/Bax Signaling Pathway and Oxidative Stress by Long-term Sodium Hydrosulfide Administration in Ovalbumin-induced Chronic Asthma.

Asthma is one of the most common respiratory diseases in the world. Nevertheless, it is reported that inflammation induced by asthma is not only restricted to the lung and may cause damaging effects on remote organs. Therefore, this study was designed to investigate the beneficial effects of long-term sodium hydrosulfide (NaHS) administration on lung inflammation and oxidative stress markers to protect the kidney during chronic asthma. BALB/c mice were divided into three groups (n = 5-7): control, asthma and NaHS. Except the control group, sensitization and challenge were performed with ovalbumin. The NaHS group intraperitoneally received 14 µmol/kg NaHS 30 min before each challenge. 24 h after the last challenge, samples of bronchoalveolar lavage fluid (BALF), plasma, lung and kidney tissues were collected. NaHS administration significantly decreased total white blood cell count, percentages of eosinophils, neutrophils and macrophages and increased percentage of lymphocytes. Administration of NaHS considerably decreased the levels of BALF interleukin-13, plasma tumor necrosis factor-alpha (TNF-α), lung malondialdehyde (MDA) and lung phosphorylated nuclear factor-kappa B (p-NF-κB) expression and scores of peribronchial inflammatory cell infiltration, goblet cell hyperplasia and subepithelial fibrosis and increased the activity of lung superoxide dismutase (SOD). The MDA levels and expressions of p-ERK1/2 and Bax were decreased and SOD activity and expressions of Bcl-2 and p-Akt were significantly increased in kidney tissues by NaHS administration. Administration of NaHS decreased renal oxidative stress indices and reduced apoptosis by the inhibition of TNF-α/ERK1/2/Bax. Therefore, H2S may have an essential role in renal protection during asthma.

Effect of Hydrogen Sulfide on Kidney Injury in Rat Model of Crush Syndrome.

BACKGROUND: Acute kidney injury is the most serious complication of crush syndrome. Hydrogen sulfide (H2S) is an endogenously produced gaseous signaling molecule. It is involved in homeostatic functions, such as blood pressure control, apoptosis, oxidative stress, and inflammation. In this study, effects of H2S on kidney injury were investigated in a rat model of crush syndrome. METHODS: Rats were divided into six groups (n = 8): Sham (steril saline ip), crush (sterile saline ip), crush + NaHS (sodium hydrosulfide, an H2S donor) (100 µmol/kg ip). All these groups were also separated as 3 and 24 h after decompression. Crush injury was induced by 6 h of direct compression to both hindlimbs of anesthetized rats with blocks weighing 3.6 kg each sides, followed by 3 or 24 h of decompression. Kidney injury molecule-1, neutrophil gelatinase-associated lipocalin, tumor-necrotizing factor-α, transforming growth factor-ß, tissue total oxidant status, and total antioxidant status levels were measured in kidney homogenates 3 and 24 h after decompression. Serum creatine kinase, blood urea nitrogen, and creatinine levels were also measured. Apoptosis was assessed by TUNEL method. Bcl-2 was assessed by immunohistochemistry. Glomerular and tubular structures were also examined histopathologically. RESULTS: NaHS reduced kidney injury molecule-1, neutrophil gelatinase-associated lipocalin, tumor-necrotizing factor-α, transforming growth factor-ß, total oxidant status levels, and increased total antioxidant status levels in kidney 3 and 24 h after decompression. Serum urea, creatinine, and creatine kinase levels also reduced with NaHS. NaHS decreased renal damage and apoptosis in crush-related acute kidney injury. CONCLUSIONS: These results suggest that H2S could reduce crush-related acute kidney injury via anti-inflammatory, antioxidant, and antiapoptotic effects.

Hydrogen sulfide improves intestinal recovery following ischemia by endothelial nitric oxide-dependent mechanisms.

Hydrogen sulfide (H2S) is an endogenous gasotransmitter that has vasodilatory properties. It may be a novel therapy for intestinal ischemia-reperfusion (I/R) injury. We hypothesized that 1) H2S would improve postischemic survival, mesenteric perfusion, mucosal injury, and inflammation compared with vehicle and 2) the benefits of H2S would be mediated through endothelial nitric oxide. C57BL/6J wild-type and endothelial nitric oxide synthase knockout (eNOS KO) mice were anesthetized, and a midline laparotomy was performed. Intestines were eviscerated, the small bowel mesenteric root identified, and baseline intestinal perfusion was determined using laser Doppler. Intestinal ischemia was established by temporarily occluding the superior mesenteric artery. Following ischemia, the clamp was removed, and the intestines were allowed to recover. Either sodium hydrosulfide (2 nmol/kg or 2 µmol/kg NaHS) in PBS vehicle or vehicle only was injected into the peritoneum. Animals were allowed to recover and were assessed for mesenteric perfusion, mucosal injury, and intestinal cytokines. P values < 0.05 were significant. H2S improved mesenteric perfusion and mucosal injury scores following I/R injury. However, in the setting of eNOS ablation, there was no improvement in these parameters with H2S therapy. Application of H2S also resulted in lower levels of intestinal cytokine production following I/R. Intraperitoneal H2S therapy can improve mesenteric perfusion, intestinal mucosal injury, and intestinal inflammation following I/R. The benefits of H2S appear to be mediated through endothelial nitric oxide-dependent pathways.NEW & NOTEWORTHY H2S is a gaseous mediator that acts as an anti-inflammatory agent contributing to gastrointestinal mucosal defense. It promotes vascular dilation, mucosal repair, and resolution of inflammation following intestinal ischemia and may be exploited as a novel therapeutic agent. It is unclear whether H2S works through nitric oxide-dependent pathways in the intestine. We appreciate that H2S was able to improve postischemic recovery of mesenteric perfusion, mucosal integrity, and inflammation. The beneficial effects of H2S appear to be mediated through endothelial nitric oxide-dependent pathways.

H2S as a possible therapeutic alternative for the treatment of hypertensive kidney injury.

Hypertension is the most common cause of cardiovascular morbidities and mortalities, and a major risk factor for renal dysfunction. It is considered one of the causes of chronic kidney disease, which progresses into end-stage renal disease and eventually loss of renal function. Yet, the mechanism underlying the pathogenesis of hypertension and its associated kidney injury is still poorly understood. Moreover, despite existing antihypertensive therapies, achievement of blood pressure control and preservation of renal function still remain a worldwide public health challenge in a subset of hypertensive patients. Therefore, novel modes of intervention are in demand. Hydrogen sulfide (H2S), a gaseous signaling molecule, has been established to possess antihypertensive and renoprotective properties, which may represent an important therapeutic alternative for the treatment of hypertension and kidney injury. This review discusses recent findings about H2S in hypertension and kidney injury from both experimental and clinical studies. It also addresses future direction regarding therapeutic use of H2S.

Signaling effects of sodium hydrosulfide in healthy donor peripheral blood mononuclear cells.

Hydrogen sulfide (H2S) is an endogenous gasotransmitter in human physiology and inflammatory disease, however, with limited knowledge of how signal transduction pathways are involved in immune cells. To examine the effects of sulfide on relevant intracellular signaling in human peripheral blood mononuclear cells (PBMCs), we stimulated healthy donor PBMCs with sodium hydrosulfide (NaHS, 1-1000µM) to mimic H2S stimulation, and analyzed phosphorylation of p38 mitogen activated protein kinase (MAPK) (pT180/pY182), NF-κB p65 (pS529), Akt (pS473) and CREB/ATF1 (pS133/pS63) with flow and mass cytometry. In contrast to transient effects in subsets of lymphocytes, classical monocytes demonstrated sustained phosphorylation of p38, Akt and CREB/ATF1. NaHS induced calcium dependent phosphorylation of p38, Akt and CREB, but not NF-κB, and the phosphorylation of Akt was partly dependent on p38, indicative of p38-Akt crosstalk. Attenuation of these effects by molecules targeting p38 and Hsp90 indicated Hsp90 as a possible target for H2S-induced activation of p38. These results provide a description of a NaHS-induced signal transduction pathway in human primary immune cells that may have relevance for the role of sulfides in inflammation.

Interaction between endogenous carbon monoxide and hydrogen sulfide in the mechanism of gastroprotection against acute aspirin-induced gastric damage.

Acetylsalicylic acid (ASA) is mainly recognized as painkiller or anti-inflammatory drug. However, ASA causes serious side effects towards gastrointestinal (GI) tract which limits its usefulness. Carbon monoxide (CO) and hydrogen sulfide (H2S) have been described to act as important endogenous messengers and mediators of gastroprotection but whether they can interact in gastroprotection against acute ASA-induced gastric damage remains unknown. In this study male Wistar rats were pretreated with 1) vehicle (saline, i.g.), 2) tricarbonyldichlororuthenium (II) dimer (CORM-2, 5mg/kg i.g.), 3) sodium hydrosulfide (NaHS, 5mg/kg i.g.), 4) zinc protoporphyrin (ZnPP, 10mg/kg i.p.), 5) D,L-propargylglycine (PAG, 30mg/kg i.g.), 6) ZnPP combined with NaHS, 7) PAG combined with CORM-2 or 8) 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, 10mg/kg i.p.) combined with CORM-2 or NaHS and 30min later ASA was administered i.g. in a single dose of 125mg/kg. After 1h, gastric blood flow (GBF) was determined by H2 gas clearance technique and gastric lesions were assessed by planimetry and histology. CO content in gastric mucosa and COHb concentration in blood were determined by gas chromatography and H2S production was assessed in gastric mucosa using methylene blue method. Protein and/or mRNA expression for cystathionine-γ-lyase (CSE), cystathionine-ß-synthase (CBS), 3-mercaptopyruvate sulfurtransferase (3-MST), heme oxygenase (HO)-1, HO-2, hypoxia inducible factor-alpha (HIF)-1α, nuclear factor (erythroid-derived 2)-like 2 (Nrf-2), cyclooxygenase (COX)-1 and COX-2, inducible nitric oxide synthase (iNOS) and interleukin (IL)-1ß were determined by Western blot or real-time PCR, respectively. ASA caused hemorrhagic gastric mucosal damage and significantly decreased GBF, H2S production, CO content, mRNA or protein expression for CSE, 3-MST, HO-2 and increased mRNA and/or protein expression for CBS, HO-1, Nrf-2, HIF-1α, iNOS, IL-1ß, COX-2 in gastric mucosa and COHb concentration in blood. Pretreatment with CORM-2 or NaHS but not with PAG decreased ASA-damage and increased GBF. ZnPP reversed protective and hyperemic effect of NaHS but PAG failed to affect CORM-2-induced gastroprotection. CORM-2 elevated CO content, mRNA or protein expression for HO-1, Nrf-2, and decreased expression of CBS, HIF-1α, COX-2, IL-1ß, iNOS, the H2S production in gastric mucosa and COHb concentration in blood. NaHS raised mRNA or protein expression for CSE, COX-1 and decreased mRNA expression for IL-1ß and COHb level in blood. We conclude that CO is involved in gastroprotection induced by H2S while beneficial protective action of CO released from CORM-2 in gastric mucosa seems to be H2S-independent. In contrast to H2S, CO ameliorates hypoxia, regulates Nrf-2 expression but similarly to H2S acts on sGC-dependent manner to restore gastric microcirculation and exhibit anti-inflammatory activity in gastric mucosa compromised by ASA.

Roles of sodium hydrosulfide and sodium nitroprusside as priming molecules during drought acclimation in citrus plants.

Emerging evidence suggests that the gaseous molecules hydrogen sulfide (H2S) and nitric oxide (NO) enhances plant acclimation to stress; however, the underlying mechanism remains unclear. In this work, we explored if pretreatment of citrus roots with NaHS (a H2S donor) or sodium nitroprusside (SNP, a NO donor) for 2 days (d) could elicit long-lasting priming effects to subsequent exposure to PEG-associated drought stress for 21 d following a 5 d acclimation period. Detailed physiological study documented that both pretreatments primed plants against drought stress. Analysis of the level of nitrite, NOx, S-nitrosoglutahione reductase, Tyr-nitration and S-nitrosylation along with the expression of genes involved in NO-generation suggested that the nitrosative status of leaves and roots was altered by NaHS and SNP. Using a proteomic approach we characterized S-nitrosylated proteins in citrus leaves exposed to chemical treatments, including well known and novel S-nitrosylated targets. Mass spectrometry analysis also enabled the identification of 42 differentially expressed proteins in PEG alone-treated plants. Several PEG-responsive proteins were down-regulated, especially photosynthetic proteins. Finally, the identification of specific proteins that were regulated by NaHS and SNP under PEG conditions provides novel insight into long-term drought priming in plants and in a fruit crop such as citrus in particular.

H2S induces vasoconstriction of rat cerebral arteries via cAMP/adenylyl cyclase pathway.

Hydrogen sulfide (H2S), traditionally known for its toxic effects, is now involved in regulating vascular tone. Here we investigated the vasoconstrictive effect of H2S on cerebral artery and the underlying mechanism. Sodium hydrosulfide (NaHS), a donor of H2S, concentration-dependently induced vasoconstriction on basilar artery, which was enhanced in the presence of isoprenaline, a ß-adrenoceptor agonist or forskolin, an adenylyl cyclase activator. Administration of NaHS attenuated the vasorelaxant effects of isoprenaline or forskolin. Meanwhile, the NaHS-induced vasoconstriction was diminished in the presence of 8B-cAMP, an analog of cAMP, but was not affected by Bay K-8644, a selective L-type Ca(2+) channel agonist. These results could be explained by the revised effects of NaHS on isoprenaline-induced cAMP elevation and forskolin-stimulated adenylyl cyclase activity. Additionally, NaHS-induced vasoconstriction was enhanced by removing the endothelium or in the presence of L-NAME, an inhibitor of nitric oxide synthase. L-NAME only partially attenuated the effect of NaHS which was given together with forskolin on the pre-contracted artery. In conclusion, H2S induces vasoconstriction of cerebral artery via, at least in part, cAMP/adenylyl cyclase pathway.

Sodium hydrosulfide inhibits the differentiation of osteoclast progenitor cells via NRF2-dependent mechanism.

Hydrogen sulfide (H2S), which recently emerged as a potent regulator of tissues and organs, is broadly produced in mammalian cells but whether it can regulate bone cell function is still elusive. The main objective of this study was to establish the role of H2S in the regulation of human osteoclast differentiation and function. Sodium hydrosulfide (NaHS), a common H2S-donor, was administered in vitro to CD11b+ human monocytes, the pool of circulating osteoclasts precursors which are critically involved in osteoclast development and function in bone. NaHS dose-dependently decreased human osteoclast differentiation at concentrations which did not induce toxicity. The inhibition of human osteoclast differentiation was associated with a down-regulation in RANKL-dependent intracellular ROS levels in human pre-osteoclasts cells. Furthermore, NaHS up-regulated NRF2 protein expression, its nuclear translocation, and the transcription of the two key downstream antioxidant genes Peroxiredoxin-1 and NAD(P)H dehydrogenase quinone 1, suggesting that NRF2 activation may inhibit human osteoclast differentiation by activating a sustained antioxidant response in osteoclast progenitors; furthermore, NRF2 activators Sulforaphane and Tert-butylhydroquinone inhibited in vitro human osteoclast differentiation. Moreover, silencing NRF2 in human pre-osteoclasts totally abolished NaHS-mediated inhibition of osteoclastogenesis, suggesting that NRF2 is essential to the inhibitory function of NaHS in osteoclast development. Finally, we found that NaHS also downregulated the RANKL/OPG mRNA ratio in human mesenchymal stem cells, the key osteoclast-supporting cells. Our results suggest that NaHS shows a potential therapeutical role in erosive diseases of bone by regulating both direct and indirect mechanisms controlling the differentiation of circulating osteoclasts precursors.

Hydrogen sulfide dilates rat mesenteric arteries by activating endothelial large-conductance Ca²âº-activated K⁺ channels and smooth muscle Ca²âº sparks.

We have previously shown that hydrogen sulfide (H2S) reduces myogenic tone and causes relaxation of phenylephrine (PE)-constricted mesenteric arteries. This effect of H2S to cause vasodilation and vascular smooth muscle cell (VSMC) hyperpolarization was mediated by large-conductance Ca(2+)-activated potassium channels (BKCa). Ca(2+) sparks are ryanodine receptor (RyR)-mediated Ca(2+)-release events that activate BKCa channels in VSMCs to cause membrane hyperpolarization and vasodilation. We hypothesized that H2S activates Ca(2+) sparks in small mesenteric arteries. Ca(2+) sparks were measured using confocal microscopy in rat mesenteric arteries loaded with the Ca(2+) indicator fluo-4. VSMC membrane potential (Em) was measured in isolated arteries using sharp microelectrodes. In PE-constricted arteries, the H2S donor NaHS caused vasodilation that was inhibited by ryanodine (RyR blocker), abluminal or luminal iberiotoxin (IbTx, BKCa blocker), endothelial cell (EC) disruption, and sulfaphenazole [cytochrome P-450 2C (Cyp2C) inhibitor]. The H2S donor NaHS (10 µmol/l) increased Ca(2+) sparks but only in the presence of intact EC and this was blocked by sulfaphenazole or luminal IbTx. Inhibiting cystathionine γ-lyase (CSE)-derived H2S with ß-cyano-l-alanine (BCA) also reduced VSMC Ca(2+) spark frequency in mesenteric arteries, as did EC disruption. However, excess CSE substrate homocysteine did not affect spark activity. NaHS hyperpolarized VSMC Em in PE-depolarized mesenteric arteries with intact EC and also hyperpolarized EC Em in arteries cut open to expose the lumen. This hyperpolarization was prevented by ryanodine, sulfaphenazole, and abluminal or luminal IbTx. BCA reduced IbTx-sensitive K(+) currents in freshly dispersed mesenteric ECs. These results suggest that H2S increases Ca(2+) spark activity in mesenteric artery VSMC through activation of endothelial BKCa channels and Cyp2C, a novel vasodilatory pathway for this emerging signaling molecule.

Hydrogen sulfide slows down progression of experimental Alzheimer's disease by targeting multiple pathophysiological mechanisms.

It has been previously reported that brain hydrogen sulfide (H2S) synthesis is severely decreased in Alzheimer's disease (AD) patients, and plasma H2S levels are negatively correlated with the severity of AD. Here we extensively investigated whether treatment with a H2S donor and spa-waters rich in H2S induces neuroprotection and slows down progression of AD. Studies with sodium hydrosulfide (a H2S donor) and Tabiano's spa-water were carried out in three experimental models of AD. Short-term and long-term treatments with sodium hydrosulfide and/or Tabiano's spa-water significantly protected against impairment in learning and memory in rat models of AD induced by brain injection of ß-amyloid1-40 (Aß) or streptozotocin, and in an AD mouse model harboring human transgenes APPSwe, PS1M146V and tauP301L (3xTg-AD mice). The improvement in behavioral performance was associated with hippocampus was size of Aß plaques and preservation of the morphological picture, as found in AD rats. Further, lowered concentration/phosphorylation levels of proteins thought to be the central events in AD pathophysiology, namely amyloid precursor protein, presenilin-1, Aß1-42 and tau phosphorylated at Thr181, Ser396 and Ser202, were detected in 3xTg-AD mice treated with spa-water. The excitotoxicity-triggered oxidative and nitrosative stress was counteracted in 3xTg-AD mice, as indicated by the decreased levels of malondialdehyde and nitrites in the cerebral cortex. Hippocampus reduced activity of c-jun N-terminal kinases, extracellular signal-regulated kinases and p38, which have an established role not only in phosphorylation of tau protein but also in inflammation and apoptosis, was also found. Consistently, decrease in tumor necrosis factor-α level, up-regulation of Bcl-2, and down-regulation of BAX and the downstream executioner caspase-3, also occurred in the hippocampus of 3xTg-AD mice after treatment with Tabiano's spa-water, thus suggesting that it is also able to modulate inflammation and apoptosis. Our findings indicate that appropriate treatments with H2S donors and Tabiano's spa-waters, and may be other spa-waters rich in H2S content, might represent an innovative approach to slow down AD progression in humans by targeting multiple pathophysiological mechanisms.

Pharmacological actions of the slow release hydrogen sulfide donor GYY4137 on phenylephrine-induced tone in isolated bovine ciliary artery.

Hydrogen sulfide (H2S), a colorless gas characterized by its pungent odor of rotten eggs has been reported to elicit relaxation effects on basal and pre-contracted non-ocular smooth muscles of several mammalian species. In the present study, we investigated the pharmacological actions of a H2S donor, GYY4137 on isolated bovine posterior ciliary artery after contraction with the adrenergic receptor agonist, phenylephrine. Furthermore, we studied the underlying mechanism of inhibitory action of GYY4137 on the posterior ciliary arteries. Isolated bovine posterior ciliary arteries were mounted in oxygenated organ baths and changes in isometric tension were measured with a Grass FT03 transducer connected to a recorder using a Grass Polyview Software. The relaxant actions of GYY4137 on phenylephrine pre-contracted arteries were observed in the absence and presence of an inhibitor of cyclo-oxygenase, flurbiprofen. Furthermore, the inhibitory effects of GYY4137 were studied in the absence or presence of inhibitors/activators of biosynthetic enzymes for H2S and nitric oxide production, as well as specific ion channel blockers. In the concentration range, 100 nM to 100 µM, GYY4137 elicited a concentration-dependant relaxation of phenylephrine-induced tone in isolated posterior ciliary arteries, with IC50 value of 13.4 ± 1.9 µM (n = 6). The cyclo-oxygenase inhibitor, flurbiprofen, significantly (p < 0.01) enhanced the relaxation induced by GYY4137 yielding IC50 value of 0.13 ± 0.08 µM (n = 6). Both the inhibitors of cystathionine ß-synthase (aminooxyacetic acid, AOAA, 30 µM) and cystathionine γ-lyase (propargylglycine, PAG, 1 mM) caused significant (p < 0.05) rightward shifts in the concentration-response curve to GYY4137. Furthermore, the KATP channel antagonist, glibenclamide (100 µM) significantly (p < 0.01) attenuated the relaxant action induced by GYY4137 on bovine ciliary artery. Conversely, the activator of cystathionine ß-synthase, SAM (100 µM) and an inhibitor of nitric oxide synthase, L-NAME (100 µM) had no significant effect on relaxations induced by GYY4137. We conclude that the inhibitory action of GYY4137 on isolated bovine ciliary artery is dependent upon the endogenous production of both prostanoids and H2S. Furthermore, the observed vascular smooth muscle relaxation induced by GYY4137 is mediated, at least in part, by KATP channels.

Sodium hydrosulfide inhibits hemin-induced ferroptosis and lipid peroxidation in BV2 cells via the CBS/H2S system.

Ferroptosis is a form of iron-dependent programmed cell death discovered in recent years that has been shown to be involved in diverse neurological disorders. Hydrogen sulfide (H2S) is an important signaling molecule with neuroprotective effects, including antioxidation. However, whether the protective mechanism of H2S is related to ferroptosis remains unknown. Therefore, in this study, we focused on the protective mechanisms of sodium hydrosulfide (NaHS, a donor of H2S) against ferroptosis caused by intracerebral hemorrhage (ICH) using a hemin-induced BV2 cell injury model in vitro. Our results indicated that NaHS enhanced cell viability and reduced hemin-induced lactate dehydrogenase (LDH) release. NaHS suppressed ferroptosis after hemin treatment, which was confirmed by attenuated reactive oxygen species (ROS) and lipid peroxidation, maintained iron homeostasis, recovery of the expression of glutathione peroxidase 4 (GPX4) and solute carrier family 7-member 11 (SLC7A11), and increased glutathione (GSH) production. Moreover, we demonstrated that inhibiting ferroptosis improved cell survival and prevented hemin-induced oxidative stress. In addition, NaHS was also able to block ferroptosis inducer RSL3-induced ferroptotic cell death. We also found that NaHS increased cystathionine-ß-synthase (CBS) expression and H2S levels after hemin treatment. Furthermore, NaHS-induced ferroptosis reduction was inhibited by the CBS inhibitor aminooxyacetic acid (AOAA) as well as by CBS small interference RNA (siCBS). In summary, these findings demonstrated that NaHS protects against hemin-induced ferroptosis by reducing lipid peroxidation, inhibiting iron overload, increasing GSH production, and improving GPX4 and SLC7A11 via the CBS/H2S system. The CBS/H2S system may be a promising target for preventing ferroptosis after ICH.

Sodium hydrosulfide moderately alleviates the hallmark symptoms of Duchenne muscular dystrophy in mdx mice.

Duchenne muscular dystrophy (DMD) is an incurable disease caused by mutations in the X-linked DMD gene that encodes a structural muscle protein, dystrophin. This, in turn, leads to progressive degeneration of the skeletal muscles and the heart. Hydrogen sulfide (H2S), the pleiotropic agent with antioxidant, anti-inflammatory, and pro-angiogenic activities, could be considered a promising therapeutic factor for DMD. In this work, we studied the effect of daily intraperitoneal administration of the H2S donor, sodium hydrosulfide (NaHS, 100 µmol/kg/day for 5 weeks) on skeletal muscle (gastrocnemius, diaphragm and tibialis anterior) pathology in dystrophin-deficient mdx mice, characterized by decreased expression of H2S-generating enzymes. NaHS reduced the level of muscle damage markers in plasma (creatine kinase, lactate dehydrogenase and osteopontin). It lowered oxidative stress by affecting the GSH/GSSG ratio, up-regulating the level of cytoprotective heme oxygenase-1 (HO-1) and down-regulating the NF-κB pathway. In the gastrocnemius muscle, it also increased angiogenic vascular endothelial growth factor (Vegf) and its receptor (Kdr) expression, accompanied by the elevated number of α-SMA/CD31/lectin-positive blood vessels. The expression of fibrotic regulators, like Tgfß, Col1a1 and Fn1 was decreased by NaHS in the tibialis anterior, while the level of autophagy markers (AMPKα signalling and Atg genes), was mostly affected in the gastrocnemius. Histological and molecular analysis showed no effect of H2S donor on regeneration and the muscle fiber type composition. Overall, the H2S donor modified the gene expression and protein level of molecules associated with the pathophysiology of DMD, contributing to the regulation of oxidative stress, inflammation, autophagy, and angiogenesis.